SX8656IWLTRT Semtech, SX8656IWLTRT Datasheet - Page 19

• Manufacturer Part Number: SX8656IWLTRT
• Description: 58T7568
• Manufacturer: Semtech

Specifications of SX8656IWLTRT

• Controller Type: Resistive Touch Screen
• Ic Interface Type: I2C, Serial
• Supply Voltage Range: 2.3V To 3.6V
• Operating Temperature Range: -40°C To +85°C
• No. Of Pins: 20
• Resolution (bits): 12bit

ADVANCED COMMUNICATIONS & SENSING
4.6
4.6.1
The chip has three operating modes that are configured using the I2C as defined in § 11 :
At power-up the chip is set in manual mode.
4.6.2
In manual mode (MAN) the touchscreen interface is stopped and conversions must be manually triggered by the
host using SELECT and CONVERT command.
When a command is received, the chip executes the associated tasks listed in table below and waits for the next
command. It is up to the host to sequence all actions.
Pen detection is performed after each CONVERT command and if pen is not detected, no touch operation is
performed. Following figures assume pen down. PENSTAT is not updated in MAN mode.
To enter MAN mode the host must send the MAN command and then set TOUCHRATE = 0.
As illustrated in figure below the CONVERT command will bias the channel, wait for the programmed settling
time (POWDLY), and run the conversion.
When the CONVERT command is used with CHAN=SEQ, multiple channels as defined in RegChnMsk are
sampled. In this case, each channel will be sequentially biased during POWDLY before a conversion is started.
At the end of each channel conversion the bias is automatically removed.
Rev 1 – 25
Figure 20 – Manual Mode – CONVERT Command (CHAN = SEQ = [X;Y]; PROXSCANPERIOD = 0)
Host Operation
Channel Conversion
Channel Conversion
Channel Bias
CONVSTAT
NIRQ (RegIrqMsk[3]=1)
Channel Bias
CONVSTAT
NIRQ (RegIrqMsk[3]=1)
I2C
I2C
Overview
Manual (command ‘MAN’ and TOUCHRATE = 0).
Pen detect (command ‘PENDET’ and TOUCHRATE > 0).
Pen trigger (command ‘PENTRG’ and TOUCHRATE > 0).
Manual Mode (MAN)
th
Figure 19 – Manual Mode – CONVERT Command (CHAN = Y; PROXSCANPERIOD = 0)
Command
CONVERT(CHAN)
SELECT(CHAN)
July 2011
CONVERT(SEQ)
Table 6 – Manual Mode Commands
Actions
Select and bias CHAN
Wait for the programmed settling time (POWDLY)
Convert CHAN
Select and bias CHAN
Resistive Touchscreen Controller with Proximity Sensing
CONVERT(Y)
POWDLY
19
X
X
POWDLY
POWDLY
SX8654/SX8655/SX8656
Y
Y
Y
Y
READ CHANNEL
READ CHANNEL
Haptics Enabled 4/5-Wire
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